[flang-commits] [flang] [llvm] [OpenMP] Introduce descriptors for directives, clause groups and sets (PR #229522)

[Tom Eccles via flang-commits]

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@@ -95,9 +147,54 @@ Clauses descriptor::ModifierSet::getClauses(Version V) const {
 const descriptor::Clause &getDescriptor(Clause C) {
   return getClauseMap().at(C);
 }
+
+const descriptor::ClauseSet &getDescriptor(ClauseSet S) {
+  return getClauseSetMap().at(S);
+}
+
+const descriptor::Directive &getDescriptor(Directive D) {
+  ArrayRef<llvm::omp::Directive> Leafs = llvm::omp::getLeafConstructsOrSelf(D);
+  if (Leafs.size() == 1)
+    return getDirectiveMap().at(Leafs[0]);
+
+  static DenseMap<Directive, descriptor::Directive> Compound;
+  if (auto F = Compound.find(D); F != Compound.end())
+    return F->second;
+
+  // Combine details from all leafs into a single map and create a descriptor
+  // from it.
+  using Details = descriptor::details::Directive;
+  using DetailsMap = descriptor::DetailsMap<Details>;
+  DetailsMap Det;
+  llvm::omp::Version MaxV(0);
+
+  for (llvm::omp::Directive L : Leafs) {
+    const auto &Desc{getDescriptor(L)};
+    for (auto &[V, T] : Desc.getDetails()) {
+      MaxV = std::max(MaxV, V);
+      auto F = Det.insert({V, Details{}}).first;
+      F->second.Spelling = getOpenMPDirectiveName(D, V);
+      // The category should be the same for all of them (i.e. executable),
+      // the association of the last one is the association of the whole
+      // directive. Since the leafs are ordered from the outermost to the
+      // innermost it is safe to simply overwrite the non-set members each
+      // time.
+      F->second.Assoc = T.Assoc;
+      F->second.Cat = T.Cat;
+      F->second.Cls |= T.Cls;
+      F->second.ClsSets |= T.ClsSets;
+    }
+  }
+
+  auto At =
+      Compound.try_emplace(D, getOpenMPDirectiveName(D, MaxV), std::move(Det));
+  return At.first->second;
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tblah wrote:

I think the descriptor will need to be returned by value. The dense map could be reallocated on any insertion: invalidating the references into its storage.

An alternative would be to return a smart pointer to the descriptor.

https://github.com/llvm/llvm-project/pull/229522